1. Field of the Invention
The invention relates to a sewing device, and more particularly to a sewing device for producing piped openings such as pocket slashes, with or without a pocket flap.
2. Description of Related Art
A sewing device for producing piped openings is disclosed in Federal Republic of Germany No. OS 22 40 617. This device includes horizontally displaceable cutting blocks having angle cutting knives which are movable vertically upward by pressing means to produce gusset cuts. These cutting blocks are mounted for lateral displacement on parallel guide rails which are fixed on a frame. Each cutting block has an adjustable stop which acts as adjustment means. This sewing device, furthermore, has two driving blocks, also horizontally movable, each of which has a driver for moving intermittently against said adjustable stop.
Also known to the art are devices for folding the piping strip, and sewing material transport devices for transporting material between a delivery point, a sewing point, and a cutting point.
By using such devices, precise agreement between the spacing of the angle cutting knives and the length of the flap, in a piped pocket slash having such a flap, is made possible.
However, in actual sewing, tolerances occur in situations such as when the material being sewn has relatively little stability of shape. These tolerances are frequently compensated for by changing the preestablished values which constitute the basic position of the automatic pocket-slash sewing machine; for instance, the points of initial insertion of the angle cutting knives, and possibly the points of the start and/or the end of the seam, according to empirically determined correction values. These readjustments, which are made, for instance, by shifting the aforementioned stops against the cutting blocks, must be manually performed by specially trained persons, and frequently in places with poor accessibility. Another disadvantage of the prior sewing devices is that no guidance aids are associated with the adjustment means for directly and precisely reading the amount of the shift.
Accordingly, a principal object of the invention is to create a sewing device in which changes may be made very simply in the pre-established values which correspond to the basic position of the automatic pocket-slash sewing machine, for changing the points of insertion of the angle cutting knives as well as the center knife, as well as the points of commencement of both seams, by inputting length-related correction values into a control unit which is provided conveniently within the reach of the operator and within his or her field of view.
With the sewing device of the invention it is now possible, starting from the basic operating position of the automatic pocket-slash sewing machine, to move the points of attack of the parallel seams, the center knive, and the angle cutting knives, individually or jointly, forward or backward over a defined path.
A further object is to provide a simplified mechanical arrangement for the device. The sewing device described above is a very suitable embodiment, in which a common drive is provided for the two-needle sewing machine, the sewing-material transport device, and the cutting device. In an alternate preferred embodiment of the invention, the two-needle sewing machine is driven by a first electric motor, and the sewing-material transport device and the cutting device are driven by at least one additional electric motor, which simplifies the mechanism substantially.
According to preferred aspects of the invention, a sewing device for producing piped openings in sewing material comprises motor means; a two-needle sewing machine having a vertically moveable center knife for cutting an opening to be piped; a cutting device including two vertically moveable angled cutting knives for performing gusset cuts; and a material transport device for receiving material to be sewn and transporting it between the sewing machine and the cutting device. The cutting device, the transport device, and the sewing machine are driven by the motor means. Also provided are control means for controlling the above elements to obtain selected interrelated movements thereof. The control means comprises at least one signal generator for generating movement signals that represent movements of the cutting device and the transport device; and a control unit including input means, a microprocessor and a ROM. The ROM stores data that represent a plurality of predetermined movements that may be performed by the various controlled elements; the input means are for receiving input data indicative of the selected movements to be performed; and the microprocessor is for controlling all the controlled elements to produce piped openings in the sewing material.
Advantageously, the input means comprises a plurality of switches. The switches are for selecting aspects of seams to be sewn by the needles, cutting to be performed by the center knive and gusset cuts to be made by the cutting device. Such data include the length of the seams and the cuts and the locations of the gusset cuts.
In one advantageous embodiment, the transport device and the cutting device are interconnected by gearing means for being commonly driven. The above-mentioned signal generator may be coupled to the gearing means for sensing movement thereof to thereby sense movement of the cutting device and the transport device. The motor means may advantageously comprise one motor which is coupled to the gearing means of the cutting device and the transport device, and also coupled to the sewing machine, for commonly driving the same. Alternatively, the motor means may comprise a first motor drivingly coupled to the sewing machine, and a second motor drivingly coupled to at least one of the cutting device and the transport device. These motors are preferably DC motors or stepping motors.